513  
FXUS61 KBOX 101742  
AFDBOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BOSTON/NORTON MA  
142 PM EDT TUE JUL 10 2018  
   
SYNOPSIS
 
 
ANOTHER HOT AFTERNOON IS ON TAP TODAY AND AN APPROACHING COLD  
FRONT WILL TRIGGER SCATTERED SHOWERS AND THUNDERSTORMS LATE  
TODAY AND TONIGHT. A FEW STRONG STORMS ARE POSSIBLE IN THE  
INTERIOR. TROPICAL STORM CHRIS IS EXPECTED TO INTENSIFY INTO A  
HURRICANE TODAY BUT PASS WELL SOUTHEAST OF NANTUCKET WEDNESDAY.  
HIGH PRESSURE WILL BUILD OVER THE REGION THURSDAY AND FRIDAY  
RESULTING IN MAINLY DRY WEATHER ALONG WITH SEASONABLE  
TEMPERATURES AND COMFORTABLE HUMIDITY LEVELS. A RETURN TO HOT  
WEATHER IS EXPECTED LATER THIS WEEKEND INTO EARLY NEXT WEEK. WHILE A  
FEW THUNDERSTORMS CAN NOT BE RULED OUT THIS WEEKEND INTO EARLY NEXT  
WEEK, DRY WEATHER LOOKS TO DOMINATE THE MAJORITY OF THE TIME.  
 

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
1PM UPDATE...  
 
NO SIGNIFICANT CHANGES TO THE FORECAST. TEMPERATURES AT 850MB  
ARE NEAR 19C AND ARE MIXING DOWN TO THE SURFACE WHERE SITES ARE  
SEEING TEMPS NEAR OR SURPASSING 90F. THE APPROACHING COLD FRONT  
IS CURRENTLY JUST SE OF THE CANADIAN/NEW YORK BORDER WHERE A  
LINE OF CU AND A FEW ISOLATED THUNDERSTORMS ARE POPPING UP.  
 
LOOKING AT SEVERAL HI-RES MODELS, THE POTENTIAL FOR ANY STRONG  
TO SEVERE THUNDERSTORMS LOOKS TO BE DIMINISHING ACROSS SNE. DRY  
AIR ALOFT DOESN'T SEEM TO MOVE OUT OF THE REGION UNTIL 00Z AND  
GIVEN THAT CURRENT DEWPOINTS ACROSS THE REGION ARE IN THE LOW  
60S AND MID 50S, SHOWERS AND THUNDERSTORMS WILL HAVE A DIFFICULT  
TIME FORMING WITH THE LACK OF MOISTURE. IN ADDITION, WESTERLY  
WINDS WILL PROVIDE MINIMAL TO NO SURFACE CONVERGENCE. THE BEST  
CHANCE FOR ANY THUNDERSTORMS DEVELOPING WILL BE ON THE EASTERN  
SLOPES OF THE BERKSHIRES AND THE WORCESTER HILLS DUE TO  
UPSLOPING WINDS. HIGHER TERRAIN IS ALSO COLOCATED WITH THE  
STRONGEST SHEAR AND INSTABILITY. THE MAIN TIME FRAME FOR STORMS  
LOOKS TO BE BETWEEN 21Z AND 02Z.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/
 
 
TONIGHT...  
 
AXIS OF DEEP MOISTURE AND KI INTO THE UPPER 30S HOLD TOGETHER AS  
FRONT DROPS SOUTH ACROSS SNE. THIS COMBINED WITH LOW LEVEL  
CONVERGENCE AND ELEVATED INSTABILITY WILL BE ENOUGH FOR  
SCATTERED SHOWERS AND A FEW T-STORMS MOVING SOUTH ACROSS SNE.  
TROPICAL PWATS ASSOCD WITH CHRIS EXPECTED TO REMAIN OFFSHORE.  
WARM EVENING, TEMPS COOLING INT THE 60S OVERNIGHT.  
 
WEDNESDAY...  
 
COLD FRONT WILL BE NEAR THE SOUTH COAST BY MORNING AND SLOWLY  
MOVING SOUTH. AT 12Z, DEEPER MOISTURE AND INSTABILITY AXIS  
HANGING ACROSS SE NEW ENG WHERE A FEW SHOWERS OR A T-STORM MAY  
LINGER INTO THE MORNING BEFORE DRYING OUT. MID LEVEL TROUGH  
PASSAGE WILL INDUCE AN INVERTED TROUGH WHICH WILL HAVE TO BE  
MONITORED FOR THE POSSIBILITY OF A FEW SHOWERS IN THE INTERIOR.  
OTHERWISE, MAINLY DRY CONDITIONS. LOW LEVEL EASTERLY FLOW IN  
POST-FRONTAL AIRMASS WILL RESULT IN A COOLER, ESPECIALLY ACROSS  
EASTERN MA. HIGHS WILL RANGE FROM THE MID 70S EAST COASTAL MA TO  
MID 80S IN THE CT VALLEY.  
 
TROPICAL STORM CHRIS IS EXPECTED TO BE A HURRICANE AS IT TRACKS  
OVER 300 MILES SOUTH OF NANTUCKET SO ONLY IMPACTS WILL BE HIGH  
SURF AND DANGEROUS RIP CURRENTS ALONG SOUTH COASTAL BEACHES.  
HIGH SURF ADVISORIES MAY BE NEEDED.  
 

 
   
LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/
 
 
HIGHLIGHTS...  
 
* MAINLY DRY THU/FRI WITH SEASONABLE TEMPS AND COMFORTABLE HUMIDITY  
 
* HOT WEATHER RETURNS LATE THIS WEEKEND INTO EARLY NEXT WEEK AND  
WHILE A FEW T-STORMS ARE POSSIBLE DRY WEATHER SHOULD DOMINATE  
 
DETAILS...  
 
THURSDAY AND FRIDAY...  
 
DISTANT TROPICAL SYSTEM CHRIS WELL EAST OF THE BENCHMARK WED EVENING  
WILL RAPIDLY MOVE NORTHEAST AND BE LOCATED EAST OF THE CANADIAN  
MARITIMES BY THU. THIS SHOULD ALLOW LINGERING SOUTHEAST SWELL/RIP  
CURRENT RISK THU TO DIMINISH BY FRI. OTHERWISE...HIGH PRESSURE TO  
OUR NORTH WILL RESULT IN MAINLY DRY WEATHER ALTHOUGH A SPOT SHOWER  
CAN NOT BE RULED OUT THU WITH A MOISTURE STARVED SHORTWAVE.  
SEASONABLE TEMPERATURES WITH COMFORTABLE HUMIDITY LEVELS ON TAP FOR  
THE REGION ON BOTH THU AND FRI.  
 
THIS WEEKEND INTO EARLY NEXT WEEK...  
 
UPPER TROUGH WILL EXIT THE REGION THIS WEEKEND ALLOWING FOR RISING  
HEIGHT FIELDS INTO EARLY NEXT WEEK. THE RESULT WILL BE THE RETURN  
TO HOT AFTERNOONS AT LEAST AWAY FROM ANY MARINE INFLUENCES ON THE  
IMMEDIATE COAST. CERTAINLY THE POTENTIAL FOR A COUPLE DAYS OF 90+  
DEGREE HEAT. SYNOPTIC SCALE FORCING DOES NOT LOOK FAVORABLE FOR  
MUCH PRECIPITATION...BUT CAN NOT RULE OUT A FEW T-STORMS. TIMING OF  
THAT RISK IS HIGHLY UNCERTAIN AND REGARDLESS THE VAST MAJORITY OF  
THIS PERIOD WILL LIKELY FEATURE DRY WEATHER.  
 

 
   
AVIATION /18Z TUESDAY THROUGH SUNDAY/
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH WEDNESDAY/...HIGH CONFIDENCE.  
 
TODAY...  
MAINLY VFR WITH SOUTHWEST WIND GUSTS NEAR 20 KNOTS DEVELOPING  
BY AFTERNOON ACROSS PORTIONS OF THE COASTAL PLAIN. SCATTERED  
SHOWERS/T-STORMS DEVELOPING AFTER 20Z ACROSS INTERIOR MA. BRIEF  
LOCALIZED MVFR-IFR CONDITIONS AND GUSTY WINDS POSSIBLE IN ANY  
T-STORMS.  
 
TONIGHT...  
SCATTERED SHOWERS/T-STORMS MOVING SOUTH ACROSS SNE. MAINLY VFR,  
BUT BRIEF MVFR-IFR POSSIBLE IN SHOWERS/T-STORMS. WINDS SHIFTING  
TO NORTH.  
 
WEDNESDAY...  
MAINLY VFR. A FEW MORNING SHOWERS MAY LINGER ACROSS SE NEW ENG.  
 
KBOS TERMINAL...HIGH CONFIDENCE IN TAF. GREATEST RISK FOR A FEW  
THUNDERSTORMS AND/OR SHOWERS IN THE VICINITY OF THE TERMINAL  
AROUND 00Z.  
 
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.  
 
OUTLOOK /WEDNESDAY NIGHT THROUGH SATURDAY/...  
 
WEDNESDAY NIGHT: VFR.  
 
THURSDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. SLIGHT CHANCE  
SHRA.  
 
THURSDAY NIGHT THROUGH FRIDAY NIGHT: VFR.  
 
SATURDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. SLIGHT CHANCE  
SHRA.  
 

 
   
MARINE
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH WEDNESDAY/...HIGH CONFIDENCE.  
 
INCREASING SW FLOW TODAY WITH GUSTS INTO THE LOWER 20 KNOTS BUT  
SEAS EXPECTED TO REMAIN BELOW 5 FT. DIMINISHING WIND TONIGHT  
WITH WIND SHIFT TO N BEHIND THE COLD FRONT. A FEW SHOWERS AND AN  
ISOLD STRONG T-STORM OR TWO WITH GUSTY WINDS POSSIBLE TONIGHT.  
NE WINDS 10-20 KT WED BUT THE MAIN CONCERN FOR MARINERS WILL BE  
THE INCREASING LONG PERIOD SOUTHERLY SWELL FROM DISTANT  
HURRICANE CHRIS. SEAS UP TO 7 FT POSSIBLE OVER SOUTHERN WATERS.  
 
OUTLOOK /WEDNESDAY NIGHT THROUGH SATURDAY/...  
 
WEDNESDAY NIGHT: WINDS LESS THAN 25 KT. LOCAL ROUGH SEAS.  
 
THURSDAY: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING  
5 FT.  
 
THURSDAY NIGHT: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING  
5 FT.  
 
FRIDAY THROUGH FRIDAY NIGHT: WINDS LESS THAN 25 KT.  
 
SATURDAY: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING 5 FT.  
 

 
   
BOX WATCHES/WARNINGS/ADVISORIES
 
 
CT...NONE.  
MA...AIR QUALITY ALERT UNTIL 11 PM EDT THIS EVENING FOR MAZ013-  
016>023.  
RI...AIR QUALITY ALERT UNTIL 11 PM EDT THIS EVENING FOR RIZ001>008.  
MARINE...NONE.  
 

 
 

 
SYNOPSIS...KJC/FRANK  
NEAR TERM...KJC/NOCERA/CORREIA  
SHORT TERM...KJC  
LONG TERM...FRANK  
AVIATION...FRANK/NOCERA/CORREIA  
MARINE...KJC/FRANK  
 
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